FullForm[expr] prints as the full form of expr, with no special syntax.

Mathematica handles many different kinds of things: mathematical formulas, lists, and graphics, to name a few. Although they often look very different, Mathematica represents ...

Using the objects described in "Introduction to Patterns", you can set up patterns for many kinds of expressions. In all cases, you must remember that the patterns must ...

Since lists are just a particular kind of expression, it will come as no surprise that you can refer to parts of any expression much as you refer to parts of a list. This ...

Here is one way to enter a particular expression. Here is another way to enter the same expression. With a notebook front end, you can also enter the expression directly in ...

Patterns are used throughout Mathematica to represent classes of expressions. A simple example of a pattern is the expression f[x_]. This pattern represents the class of ...

-x is the arithmetic negation of x.

Like everything else in Mathematica, the textual forms of expressions can themselves be represented as expressions. Textual forms that consist of one-dimensional sequences of ...

LeafCount[expr] gives the total number of indivisible subexpressions in expr.

Converting from strings or boxes to expressions. This takes a string and interprets it as an expression. Here is the box structure corresponding to the textual form of an ...